Pots for plants such as flowers, ivy, etc. have been available for decades. They generally are round in horizontal cross section, although some are square or have an even different shape.
Pots offer the gardener an opportunity to grow plants that they might otherwise be unable. Permanent pots enable the associated plants to be moved to locations having the best light, protection from extremes of weather, etc. Permanent pots are often unglazed clay because the clay is minimally water-permeable and quite inexpensive. Other permanent pots are often highly decorative and glazed to protect the decoration. The permanent pots almost universally have a central hole in the bottom of the pot to allow excess water to flow through so that a plant's roots are not continually standing in water.
Typically, the pots, such as clay pots, glazed or unglazed, are fragile and need to be on a substantial horizontal surface. Other permanent pots may be made from a variety of plastics and are reasonably durable, although not unbreakable. Permanent plastic pots also require placement on a substantial horizontal surface. Placement on sloping or uneven surfaces usually results in the pot and plant falling to an ignominious end.
Accordingly, what is needed in the art is a plant pot that can be placed on uneven surfaces without risk of falling.